Reflective paint is a type of paint that contains thousands of little glass spheres, designed to reflect lots of light, even at night. It is most frequently used for signs on highways, but is also used on license plates, fishing lures, on mobile objects to be tracked (like a golf ball), or as an indicator on certain machinery. The size of glass beads ranges from application to application, but generally, the smaller the bead, the more expensive it is. The beads are sprayed on after paint is applied for the most even possible distribution. The beads are applied over a colored base coat designed to yield maximum reflectivity.
The typical glass beads used in reflective paint on highways are fairly inexpensive, and they are usually mixed with yellow latex paint. This paint is designed to be clearly visible when illuminated by headlights, but is often visible even without headlights due to ambient light. During the day, the paint is bright, but not bright enough to be excessively distracting or blinding. Reflective paint is very useful because materials that glow independently, without constantly needing to be "recharged," are expensive and radioactive.
One common use of this paint on the highway is on "Botts' dots," the little dots used to separate highway lanes from each other. The introduction of these reflective dots has resulted in a marked increase in highway safety.
Another variety is used on the reflective surfaces of light fixtures. This paint does not have embedded glass beads, but is designed to be as reflective as possible for a normal paint coating.
Other variants of reflective paint are designed to reflect away thermal as well as optical energy. These insulators are meant to be applied to the outside of buildings in hot locations to save on air conditioning bills. Some types reflect away 44% or more of the sunlight's energy.